THE MAJOR ERYTHROID DNA-BINDING PROTEIN GATA-1 IS STIMULATED BY ERYTHROPOIETIN BUT NOT BY CHEMICAL INDUCERS OF ERYTHROID-DIFFERENTIATION

The expression of the major erythroid DNA-binding protein GATA-1 was s tudied during erythropoietin and chemically induced erythroid differen tiation of J2E and murine erythroleukemia (MEL) cells. An increase in GATA-1 mRNA levels was observed shortly after hormonal stimulation of J2E cells, due to increased transcription and not stabilization of the short-lived transcripts. Concomitantly, an increase in protein capabl e of binding to the GATA motif was detected. Premature removal of eryt hropoietin from culture resulted in submaximal GATA-1, globin, and hem oglobin production. In contrast, differentiation of J2E cells initiate d by sodium butyrate resulted in a sudden depletion of GATA-1 transcri pts. Similarly, dimethyl sulphoxide induction of MEL cells produced a transient decrease in GATA-1 mRNA. Surprisingly, these decreases in mR NA were not reflected in alterations to GATA-1 protein content, or the ability of the transcription factor to bind DNA. We concluded from th is study that the sequence of events initiated by erythropoietin was n ot followed during chemical stimulation of erythroid differentiation.